1. Field of the Invention
The invention is generally directed to antennas and their use in wireless communication.
2. Description of Related Art
Wireless communication systems typically involve information from individual wireless or landline callers being sent to and from other wireless or landline callers via base stations and wireless communication switching centers. Each base station typically includes three antennas, or a single three component antenna 20 as shown in prior art FIG. 1 (which is most times a 3 pole or 3 component antenna as represented by element 20A, 20B and 20C). The coverage area or cell 10 serviced by the base station antenna 20 varies in size, depending upon the strength or power of the antenna; the distance between base station antennas 20; and other various parameters.
Base station antenna 20 typically includes three antenna components 20A, 20B and 20C, each component being set up and remaining in a fixed position. Each of the three antenna components 20A, 20B and 20C provides a fixed beam pattern and orientation covering a fixed sector such as that shown in FIG. 1, and represented by elements 30A, 30B and 30C. The beam patterns 30A-C as shown in FIG. 1 dictate the area or sector from which information can be received from wireless communication units and to which information can be sent.
When configuring a wireless communication network, base station antennas 20 must be deployed in a manner which adequately services the wireless network. Each antenna must adequately cover its corresponding cell or area to minimize calls being dropped and to maximize the number of calls which the antenna and network can handle. A major problem in a deployment of a wireless system, such as a cellular/PCS system, lies in the deployment of base stations and their antennas, and evaluating and tuning the performance of the entire system so as to minimize dropped calls, failed acceptances of newly originated calls, and so as to maximize end-user voice quality. Thus, in the deployment of a wireless communication system, the needs exist for reducing the cost of measuring system performance; reducing the cost of collecting performance data for reiterations and adjustments and for maximizing the use of this data; and for reducing the cost associated with tuning and retuning large base station antennas such as base station antenna 20 of FIG. 1, which essentially cover fixed areas and remain fixed until physically adjusted.
Typically, when establishing a wireless communication system or network, general criteria for establishing base station location and antenna configuration are determined. Then, these established base station antennas are tested and xe2x80x9ctunedxe2x80x9d. Such an aspect of tuning is shown in prior art FIG. 2 for example. In such a system, the base station antenna 20, including three antenna components 20A, 20B and 20C, are set up in the initial xe2x80x9capproximatedxe2x80x9d position for servicing cell area 10. Then tests are done by driving a wireless mobile unit around the coverage area of base station antenna 20, namely driving the wireless mobile unit around roads 40 in a car 50, for example. From these tests, signal measurements are made to determine gaps in the coverage area, etc. Once the appropriate measurements are made, then the antenna can then be physically adjusted to positions 20Axe2x80x2, 20Bxe2x80x2and 20Cxe2x80x2 as shown in prior art FIG. 2. As can be recognized, however, there are tremendous costs in collecting data by driving the wireless mobile unit around in a car 50; and there are even further costs in physically adjusting a base 20 station antenna 20, such as the cost of physically climbing a tower and physically adjusting the positions of the antenna components of base station antenna 20. Further, as roads do not exist throughout a cell, certain areas remain untested.
In establishing a wireless communication network, additional adjustments must be made for base station antennas 20 covering a plurality of cells over the entire wireless communication network region. As shown in prior art FIGS. 1 and 2 by the dash lines, each cell 10 includes neighboring cells, with each neighboring cell similarly including a base station antenna 20 with antenna components 20A, 20B, and 20C for handling traffic load within a neighboring cell. There are costs not only associated with establishing coverage areas and xe2x80x9ctuningxe2x80x9d base station antennas 20 in a neighboring cell, but there are also cell-to-cell costs including costs associated with xe2x80x9chanding offxe2x80x9d calls from one base station antenna 20 in one cell 10 to another base station antenna 20 in a neighboring cell. These costs include establishing neighbor lists, listing the neighboring cells to which calls may be handed off and from which calls may be received.
Due to the costs associated with neighboring cells, balances must be struck in tuning the base station antennas 20, so as to minimize interference among antennas without sacrificing areas of coverage. These objectives are traditionally realized by successively driving wireless mobile units in cars 50; comparing pilot signal information and flagging dropped calls; and adjusting neighbor sites. By performing manual antenna adjustments, however, network configurations are slowly established and not always accurate. Further, although adjustments among neighboring cells is possible using techniques such as up-tilt and down-tilt of antennas and by adjustment of the transmit power sent from the base station (the base band control rate or BCR), these processes are slow and often times neglected due to the manpower costs of climbing towers and physically adjusting antennas, and/or the costs associated with tower adjustment including interference and calls being dropped. Since attenuation of transmit power is easier than physically climbing a tower and adjusting up-tilt or down-tilt of antennas, power attenuation is often chose over up-tilting and down-tilting. However, attenuation in base station transmit power may potentially create a coverage hole where a wireless call may inadvertently be dropped or be unable to be connected. Thus, when such adjustments are made, this again increases costs. Accordingly, a need exists for establishing antenna configurations which maximizes coverage within a cell, and among several neighboring cells, and which minimizes interference.
A system and method have been developed wherein a cylindrical antenna array is configured and reconfigured in a wireless communication network. Position and signal information are monitored from wireless mobile units using the network with cylindrical antenna arrays in an initial configuration, and this information is used to determine reconfigurations of antenna components of the cylindrical antenna array to enhance performance of the system. As such, base station antennas can be dynamically configured to minimize such things as interference and dropped calls, and to maximize their voice quality both within a cell, and among neighboring cells.